1. Technical Field
The present disclosure relates to a low water-vapor permeable composite film. More particularly, the present disclosure relates to a low water-vapor permeable composite film which is flexible and has high transparency.
2. Description of the Related Art
Air, water vapor and oxygen, in particular water vapor, are the main causes for the degradation of the active layer and low work function electrodes in optoelectronic devices. Thus, a low water-vapor permeable layer capable of blocking water vapor is needed for optoelectronic devices, such that the performance and life span of the optoelectronic devices are capable of being maintained and extended.
Among common materials such as plastics, glass and metals, plastics such as polyimide, polynorbornene or polyethylene naphthalate have poor water vapor barrier properties and are only suitable for anti-scratch usages in optoelectronic devices. Although glass has better water vapor barrier properties, its disadvantages of high energy consumption in fabrication, brittleness, no flexibility, bulk and heavy weight limit its applications. Metals such as aluminum foil have disadvantages of high energy consumption in fabrication, not being recyclable, high conductivity and opacity. These disadvantages make metal foils not suitable for the water vapor barrier layers in optoelectronic devices.
Since single material alone cannot meet the requirements of water vapor barrier layer in optoelectronic devices, some composite materials, for example, polymer substrates vacuum evaporated with metal or silicon oxide films, have been proposed. The composite materials have better water vapor barrier properties than plastics and are also flexible. However, the water vapor barrier properties and opacity of these composite materials still fall short of the requirements of the gas barrier layer in optoelectronic devices.
Therefore, a low water-vapor permeable film which has high transparency, good water vapor barrier properties and high flexibility is needed for optoelectronic devices.